Re: BEFORE "Negotiating" a curve.

[John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>]

On Tue, 9 Nov 1999, brian whatcott wrote:

> > 2) What is its nature? Why is it directed along -y?
>
> The rolling energy is lost to less than perfect resilience of
> the roller and of the floor. Along -y because you defined the
> rolling direction as y. So the velocity decays with a component
>  along -y because there is an upward force on the roller applied
>  by the floor with a small component in the -y direction.

I find it to be one of those wondrous things about this discipline that,
irrespective of any speculation about the precise nature of the mechanism
that provides the "force in the -y direction," you know it simply *has* to
be there.

Indeed, while I can cite mechanisms that will produce such a force, it's
not at all a priori obvious (at least to me) that every conceivable
mechanism will do so.  Nonetheless, the forward motion of the roller
represents organized energy that, in the real world, *will* be dissipated
and without such a force it can't *even* be reduced.

John Mallinckrodt      mailto:ajm@csupomona.edu
Cal Poly Pomona          http://www.csupomona.edu/~ajm